Among the camptothecin derivatives, such as topotecan and irinotecan, many have now reached the clinic as a promising anticancer agent, and camptothecin is isolated from natural products. To study the history of development, we heed a basic understanding about the research in natural products in recent years, and the difficulties in the course of drug development. This article has been subdivided into six major sections: (1) The discovery of camptothecin. (2) Structure determination of camptothecin. (3) The low ebb of development. (4) The discovery of novel mechanisms of action. (5) Structure activity relationships of camptothecin. (6) The strategy in the production of camptothecin.